Process for producing cyclic compounds

ABSTRACT

The invention includes methods of processing an initial di-carbonyl compound by conversion to a cyclic compound. The cyclic compound is reacted with an alkylating agent to form a derivative having an alkylated ring nitrogen. The invention encompasses a method of producing an N-alkyl product. Ammonia content of a solution is adjusted to produce a ratio of ammonia to di-carboxylate compound of from about 1:1 to about 1.5:1. An alkylating agent is added and the initial compound is alkylated and cyclized. The invention includes methods of making N-methyl pyrrolidinone (NMP). Aqueous ammonia and succinate is introduced into a vessel and ammonia is adjusted to provide a ratio of ammonia to succinate of less than 2:1. A methylating agent is reacted with succinate at a temperature of from greater than 100° C. to about 400° C. to produce N-methyl succinimide which is purified and hydrogenated to form NMP.

RELATED PATENT DATA

This patent claims benefit of priority under 35 U.S.C. §119 to U.S.Provisional Patent Ser. No. 60/435,469, which was filed Dec. 20, 2002.

TECHNICAL FIELD

The invention pertains to methods of processing di-carbonyl compounds,methods of producing cyclic compounds comprising a heteroatom ringmember, including N-alkyl succinimide, and methods of producingpyrrolidinones.

BACKGROUND OF THE INVENTION

Cyclic compounds such as pyrrolidinones, N-substituted pyrrolidinones,other cyclic amines, and other cyclic compounds having one or morehetero-atom ring members, are useful as solvents, anti-fungal agents,pesticides, herbicides, anticorrosion agents, antioxidants, UVprotectants, for use in forming polymers and plastics, and as reagentsfor forming other useful compounds. Conventional methods of formingthese compounds can be expensive and inefficient. It would be desirableto develop processes for production of cyclic amines and other cycliccompounds.

SUMMARY OF THE INVENTION

In one aspect the invention encompasses a method of processing aninitial di-carbonyl compound. The initial compound is converted to acyclic compound having a ring nitrogen atom and two carbonyl groups. Thecyclic compound is reacted with an alkylating agent to form a derivativehaving an alkylated ring nitrogen. The alkylated cyclic compound isproduced in a mixture containing additional components and apurification process is performed to remove at least some of theadditional components.

In one aspect the invention encompasses a method of producing an N-alkylproduct. An initial solution is provided to a reactor, the initialsolution comprises a di-carboxylate compound and ammonia, where theratio of ammonia to the di-carboxylate compound is from 0:1 to greaterthan 2:1. For purposes of the description, when referring to a solutionor mixture the term ammonia is intended to encompass either or both NH₃and NH₄ ⁺, unless specifically indicated otherwise. The amount ofammonia in solution is adjusted to produce a solution having a secondratio of ammonia to di-carboxylate compound of from about 1:1 to about1.5:1. An alkylating agent is added to the solution having the secondratio and the initial compound is alkylated and cyclized to produce acyclic N-alkyl product.

In one aspect the invention encompasses a method of making N-methylpyrrolidinone. An aqueous mixture comprising ammonia and succinate isintroduced into a vessel. The amount of ammonia in the aqueous mixtureis adjusted to provide a ratio of ammonia to succinate of from about 1:1to less than about 2:1. A methylating agent is introduced into thevessel and is reacted with succinate at a temperature of from greaterthan 100° C. to about 400° C. to produce N-methyl succinimide. TheN-methyl succinimide is at least partially purified and is subsequentlyhydrogenated to form a product mixture comprising N-methylpyrrolidinone.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a block-diagram flowchart view of a generalized methodencompassed by the present invention.

FIG. 2 is a process flow diagram showing a processing system that can beused in performing particular aspects of the present invention.

FIG. 3 is an illustration of potential equilibrium reactions that canoccur in a particular aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

In general, methods according to the present invention can be utilizedto produce a cyclic nitrogen-comprising compound having formula (I),

where R₁ is a linear or branched, saturated or unsaturated hydrocarbonor substituted hydrocarbon. Preferably, R₁ contains twenty or fewernon-hydrogen atoms, and in particular instances can preferably comprisefrom 1–10 carbon atoms. Alternatively, R₁ can be absent such that theresulting product is a three membered nitrogen comprising ring compound.R₂ can be an alkyl (linear, cyclic or branched, saturated orunsaturated), a substituted alkyl group, an aromatic group or hydrogen.

R₁ can preferably be a branched or un-branched, saturated orunsaturated, substituted or non-substituted group which allows the ringstructure of formula (I) to be a 5-, 6- or 7-membered ring. Inparticular instances, the formula (1) compound can have one of the 5- or6-membered ring formulas shown in Table 1, where R₃ through R₈ are notlimited to any particular groups, and can be independently selected fromhydrogen, hydroxyl, hetero-atom comprising functional groups, linear orbranched groups, and saturated or unsaturated groups, includinghydrocarbon groups or substituted hydrocarbons.

TABLE 1 Example Formula (I) Compounds 5-member ring compounds 6-memberring compounds

The product having formula (I) can optionally undergo furtherderivatization in accordance with a second aspect of the invention toproduce a compound having formula (II).

where R₂ is any of the substituents set forth above with respect to R₂,and R₁ is any of the groups indicated above with respect to R₁. Theinvention also contemplates three membered ring compounds analogous tothe formula II compound where R₁ is absent. The invention can beparticularly useful for production of N-methyl succinimide (NMS), aformula I compound, which in accordance with the second aspect of theinvention can optionally be utilized for production of N-methylpyrrolidinone, ((NMP), also known as N-methyl pyrrolidone).

For simplicity of description, the various methods and aspects of theinvention will be described in terms of production of NMS and/or NMP.However, it is to be understood that the described methods and aspectscan be adapted for production of any of the compounds having formula (I)or (II) set forth above.

Methods encompassed by the present invention are described generallywith reference to FIGS. 1–2. Referring initially to FIG. 1, a precursorcompound can be provided in an initial step 10. The precursor providedin step 10 can comprise a compound having formula (III).

where Z and X independently comprise one or more C, H, O, N, S, ahalide, and a counter-ion. In particular instances one or both of Z andX can be selected from OH, OR, and O⁻ (free or with a counterion). R₁can be any of the groups set forth above with respect to R₁.Alternatively, the precursor can be a compound analogous to formula(III) where R₁ is absent.

In particular embodiments, the initial compound utilized in process 10can be succinic acid or a succinic acid derivative such as, for example,a monoester, a diester, succinate, succinamic acid, a succinamic ester,succinamide, and N-alkylated succinimide, a substituted succinic acid(e.g. itaconic acid) or a succinate salt. Where a succinate salt isutilized, the counter-ion is not limited to a particular species and insome aspects can preferably be ammonium. Alternatively, the precursorprovided in step 10 can be one of the following acids or a derivativethereof: fumaric, itaconic, malic, maleic, aspartic, citric andglutamic.

The process of providing the precursor can preferably comprise formingan aqueous mixture containing the desired precursor. In particularinstances, process 10 can include a fermentation process where theprecursor is a fermentation product. For purposes of the description,methods of the present invention will be further described utilizingsuccinic acid or a derivative thereof as an exemplary starting materialfor utilization in process 10. Such can be produced by fermentation andin particular instances can be provided in process 10 in a fermentationbroth (where fermentation broth refers to an aqueous mixture having someor all of the components present in the fermentation reaction retainedin the mixture). It is to be understood that the methods can alsoutilize succinic acid derivatives or other precursor compounds producedby means other than fermentation.

Where succinate is provided as the precursor, such can preferably beprovided as ammonium succinate in an aqueous mixture or aqueoussolution. For purposes of the description that follows, all ratios referto mole ratios unless otherwise indicated, and all percents are basedupon weight unless otherwise indicated. Where a fermentation process isutilized to produce the succinate, an initial fermentation broth can inparticular instances comprise a ratio of ammonia to succinate of fromless than 1:1 to greater than or equal to 2:1. Further, the fermentationbroth can comprise from about 3–30% ammonia succinate by weight relativeto the total weight of the mixture (after filtration removal of cellularcomponents; see below). Optionally, the amount of water can be reducedin the mixture by performing a concentration step. The concentrationstep can produce a solid form of ammonium succinate, or can produce amixture of ammonia and succinate in water. Where a mixture is produced,the mixture can have from about 10% to about 80% of ammonium succinate(or ammonia and succinate) by weight, preferably approximately 50%.

Process 10 can optionally comprise adjustment of the ammonia content ofthe mixture. Where succinate is produced by a fermentation process, theadjustment can provide a final ammonia to succinate ratio of less than2:1. Preferably, the final ammonia to succinate ratio will be less thanabout 1.8:1, more preferably from about 1:1 to about 1.5:1, and mostpreferably will be between 1.2:1 and 1.4:1. Such adjustment cancomprise, for example, removal of ammonia.

Alternatively, where process 10 does not comprise a fermentation processor where succinate is provided in a non-ammonia form, ammonia can beadded to the mixture in step 10 to provide the desired ratio of ammoniato succinate. It can be advantageous to provide an ammonia to succinateratio of less than 2:1 in the mixture to optimize the subsequentreaction performed in process 12 (discussed below).

Where process 10 involves fermentation, the fermentation broth producedduring fermentation can optionally undergo a filtration step to removecells and/or at least some cellular components present in thefermentation broth prior to reaction step 12. It is to be noted,however, that the filtration is optional. Accordingly, in certaininstances a reaction broth can be provided to step 12 without beingsubjected to any of the filtration, concentration or ammonia adjustmentsteps discussed above. It is to be understood that the inventionencompasses utilization of none or any combination of the ammoniaadjustment, succinate concentration and fermentation broth filtrationsteps described.

The precursor provided in process 10 can be subjected to an alkylationand cyclization process 12 to form a cyclic product as shown in FIG. 1.The alkylation and cyclization of process 12 can be conductedconcurrently, or cyclization can be followed by alkylation. For purposesof the description, where alkylation and cyclization are conductedconcurrently, no reaction sequence or mechanism is implied. The reactionprocess 12 can be conducted under thermal conditions in the absence ofany added catalyst or can alternatively be conducted in the presence ofa catalyst, such as an acidic catalyst. Thermal conditions utilized inproducing the cyclic compound in process 12 preferably utilize atemperature of from at least 100° C. to about 400° C. In particularinstances the thermal conditions utilize a temperature of between 100°C. and 300° C. It is to be understood that the invention alsoencompasses producing non-alkylated cyclic compounds, and accordingly,the described conditions can be utilized in an absence of addition ofalkylating agent.

Process 12 can comprise thermal cyclization of at least some of theprecursor prior to addition of any alkylating agent or can compriseaddition of an alkylating agent prior to or at initiation of thecyclization reaction. The alkylating agent provided to process 12 is notlimited to a particular reagent and can be any alkylating agent toproduce the desired R₂ group. Exemplary alkylating agents appropriatefor process 12 include, but are not limited to, an alcohol, a glycol, apolyol, an epoxide and aziridine, urea, an acetal, a thiol, acarboxylate, an alkyl halide, an alkyl amine, a carbonate compound, athiol compound, a thiol-carbonate compound, a sulfate compound andmixtures thereof. In particular instances, it can be preferable toutilize an alcohol as the alkylating reagent. The alcohol can beprovided at, for example, a ratio of from about 1:1 to about 30:1relative to the succinate or alternative precursor. A preferable ratioof alcohol to precursor can be from 1:1 to about 10:1. For instance,where the desired product is NMS, methanol can be added to the reactionsuch that at initiation the reaction has a methanol to succinate ratioof from about 1:1 to about 10:1. In particular instances, the methanolto succinate can preferably be from about 1:1 to about 3:1, and morepreferably from about 1.5:1 to about 2:1.

Reaction process 12 can optionally include an immediate quench coolingor flash cooling. An exemplary quench cooling process can comprisecooling from the reaction temperature to below 100° C. in a time of lessthan or equal to about 30 minutes. It can be advantageous to quench orflash cool the reaction mixture to inhibit ring opening and to maximizeyield of the cyclic alkylated product. The processing of step 12 can beutilized to form, for example, compounds of formula (I) discussed above.

The cyclic alkylated compound produced in process 12 can optionally becollected in a collection process 14 as shown in FIG. 1. It is to beunderstood that in some instances, such as where the cyclic alkylatedcompound will undergo further conversion or derivatization, thecollection step may be omitted. Collection process 14 at least partiallypurifies the cyclic alkylated products by removing at least some of anypotentially detrimental fermentation broth components, alkylating agentsand/or byproducts produced during process 12. For purification purposesit can be advantageous that R₂ be a group which confers or enhancesproperties useful in purification such as volatility, hydrophobicity,etc. Alternative purification methods appropriate for process step 14include but are not limited to distillation, sublimation, decanting,steam distillation, extraction and crystallization. Successivepurification steps can be utilized to improve product purity. Inparticular instances, it can be preferable that a compound of formula(I) produced in step 12 be volatile to allow separation by distillation.In instances where the cyclic product will be further processed inaccordance with aspects of the invention, it can be advantageous toutilize a distillation process for purification. Where subsequentprocessing is to be conducted under thermal conditions, the distillationproduct can be directly provided to the downstream process without anintervening cooling step.

Although the reaction and distillation is described above as occurringindependently, it is to be understood that the invention additionallyencompasses concurrent reacting to form the cyclic product (whether itbe alkylated or non-alkylated), and purification of such product as itis formed. For example, concurrent reaction and purification can beconducted by reactive distillation.

As indicated above, cyclization and alkylation process 12 can optionallybe conducted in the presence of components of a fermentation broth.However, it can be advantageous to purify the product compound havingformula (I) prior to any subsequent processing in order to avoiddetrimental effects upon any catalyst which may be utilized during thesubsequent processing.

The compound of formula (I) collected and/or partially purified inprocess 14 can be further processed by carbonyl reduction process 16 orcan alternatively be utilized to form other useful products (not shown).Carbonyl reduction processing 16 can comprise hydrogenation of theformula (I) compound to produce one or more of a compound having aformula (II), a compound having a formula (IV), a compound having aformula (V), and a compound having formula (VI).

Preferably, where two or more of formulas (II), (IV), (V) and (VI) areproduced in a product mixture in process 16, compound formula (II) isthe majority product. More preferably compound of formula (II) isselectively produced relative to each of the other three products. Inparticular instances the product mixture can comprise at least 90%compound (II).

Carbonyl reduction process 16 can utilize a reduction catalyst in thepresence of hydrogen. Although the description emphasizes selectiveproduction of a compound of formula (II), it is to be understood thatthe invention encompasses selective production of any of the compoundshaving formulas (IV, V and VI). Conversion efficiency and/or selectivitycan be dependent upon various conditions utilized in process 16including, for example, the specific catalysts utilized, purity of thestarting material, length of exposure to the catalyst, hydrogenpressure, reaction temperature, the amount of water present (if any),etc. Appropriate catalysts for utilization in process 16 can preferablycomprise one or more of Fe, Ni, Pd, Pt, Co, Sn, Rh, Re, Ir, Os, Au, Ru,Zr, Ag and Cu. The catalyst can additionally comprise a support such asfor example a porous carbon support, a metallic support, a metallicoxide support or mixtures thereof. In particular instances the catalystcan contain a catalytic metal on a support containing both metal oxideand carbon. For purposes of the invention, the carbon support can be agranular carbon or carbon powder and in particular instances, thecatalytic metal(s) can be edge-coated onto the carbon support.

In instances where the compound having formula (I) collected in process14 is NMS, and selective production of NMP in process 16 is desired, thehydrogenation catalyst utilized can preferably comprise one or more ofRe, Rh, Zr, Ni, Ru, Pt, Pd and Co. Particularly useful catalysts forselective production of NMP are listed in Table 2, along with thecommercial source where appropriate.

TABLE 2 Conversion catalysts Catalyst Source Number DescriptionSynthesized 1  2.5% Re on Calgon 120 CTC granular C (uniform metaldistribution) Synthesized 2  2.5% Rh 2.5% Zr on Calgon 120 CTC C (mixedmetal distribution) Synthesized 3  2.5% Ni 2.5% Re on Norit ROX 0.8 mm Cextrudate (Uniform metal distribution) Synthesized 4  2.5% Rh 2.5% Re onNorit ROX 0.8 mm C extrudate (Uniform metal distribution) *EngelhardCorp. 6757-09-1  2.5% Ru on PICA 12 × 20 mesh granular C *EngelhardCorp. ESCAT 268    5% Pt on C powder (uniform metal distribution;pre-reduced; water-wet) *Engelhard Corp. ESCAT 340    5% Rh on C powder(mixed-metal distribution; pre-reduced; water-wet) *Engelhard Corp.ESCAT 140    5% Pd on C powder (mixed-metal distribution; pre-reduced;water-wet) *Engelhard Corp. ESCAT 440    5% Ru on C powder (mixed-metaldistribution; pre-reduced; water-wet) *Engelhard Corp. Co-0138 E ~30% Coon 3-finned alumina 1/16 3F extrudate (dry; pre-reduced; passivated)**Degussa Corp. G 106 B/W    5% Rh on C powder (pre-reduced; 5% Rh waterwet) *Engelhard Corporation, Iselin, New Jersey; **Degussa, Germany

In instances where NMS produced in step 14 is utilized for production ofNMP, efficiency and selectivity can be enhanced by performinghydrogenation process 16 in the presence of no water or very littlewater (for example less, than or equal to about 10%, by weight).Accordingly, it can be preferable to provide the product of process 14to reduction reaction 16 in solid or molten form. Further, the formula(I) compound can be provided to process 16 in molten form directly fromany high temperature purification step performed in process 14 and thusincrease time efficiency by avoiding an additional cooling step.

An appropriate reaction temperature for conversion of NMS in process 16can be from about 120° C. to about 220° C. Alternative temperatures canbe utilized for alternative conversion/hydrogenation reactions.

Utilization of the above conditions for reduction process 16 typicallyresults in a product mixture containing very little, if any, of productshaving formula's (IV) or (V). In other words, products of formula (IIand VI) are typically the primary products produced during step 16.Compounds having formula (II and IV) can be separated from otherreaction components, any products (IV) and (V) present and canoptionally be separated relative to each other in separation process 18.Compound having formula (II) can be separated from other components inthe mixture using, for example, one or more of distillation,crystallization, ion exchange and selective adsorption.

Referring to FIG. 2, a system 20 is shown which can be utilized inparticular aspects of the invention for producing a compound havingformula (I) and/or a compound having formula (II). Although system 20 isdescribed below relative to production of NMS and/or NMP, it is to beunderstood that system 20 can be adapted for production of alternativeformula (I) compounds and/or formula (II) compounds utilizingalternative reagents as set forth above.

A succinic acid derivative can be provided from a source 30 into aninitial process reactor 32. Source 30 can be, for example, afermentation processor where the fermentation produces succinate.

Where source 30 comprises fermentation, such fermentation can beperformed in corn steep liquor with added glucose and ammonia. At leastsome of the glucose and ammonia are converted into diammonium and/orammonium succinate. The succinate fermentation product can be provideddirectly to reactor 32 in the original state of the fermentation broth.Alternatively, the fermentation broth can be filtered to remove cellsand/or cellular components prior to introduction into reactor 32. Atypical succinate concentration of an original fermentation broth (afterfiltration) can be from about 3% to about 30%, by weight. The succinatecan be concentrated prior to or after providing it to reactor 32, andcan preferably be concentrated to comprise a final succinateconcentration of approximately 50%. Water can be recovered during theconcentration step and recycled along recycle route 31 back to source30.

An initial ammonia content of the fermentation broth can be adjusted inreactor 32. Such adjustment can comprise removal of ammonia from reactor32. Ammonia-removal can be conducted at a temperature of from about 130°C. to about 200° C. The ammonia can be recovered and recycled alongrecycle route 31 to source 30. The removal of ammonia can be utilized toproduce a final preferable ammonia to succinate ratio of between 1.2 and1.4.

As shown in FIG. 2, the resulting ammonia adjusted mixture can beprovided into a second reactor 34 for further reaction. Alternatively,reagents can be added to reactor 32 for further reaction processes (notshown). The mixture containing succinate provided to reactor 34 can beadded to reactor 34 prior to, after, or simultaneous to addition ofalkylating agent from a reagent source 36, and alkylation andcyclization can be conducted concurrently. Alternatively, the succinatecan be cyclized in reactor 34 prior to addition of any alkylating agent.NMS can be produced in reaction chamber 34 by addition of a methylatingagent such as, for example, methanol. Where methanol is utilized inproducing NMS in reactor 34, the methanol can be added to reactor 34 ata methanol to succinate ratio of from 1 to about 30. Preferably,methanol is added to a ratio of from about 1.5:1 to about 3:1, relativeto succinate. In particular instances, it can be preferable to provide amethanol to succinate ratio of about 2:1.

Conversion to NMS can be performed under thermal conditions withoutadditional catalysts. Alternatively, a catalyst can be added to reactor34. An exemplary catalyst for addition to reactor 34 is an acidiccatalyst.

Conversion to NMS in reactor 34 can be conducted at a reactiontemperature of from above about 100° C. to about 300° C., preferablyabout 280° C. An appropriate reaction temperature can depend upon theamount of water present, with an increased temperature enhancingefficiency at higher water content.

Various equilibrium reactions can occur within reactor 34. Exemplarypotential equilibrium reactions are shown generally in FIG. 3. Theequilibrium positions are not indicated in FIG. 3, and can be affectedby various factors such as reactant concentration, water content, andammonia to succinate ratio. Due to the reversibility of the, ringclosure, it can be advantageous to quench or flash cool the conversionreaction. Quenching can comprise, for example, cooling the reaction to atemperature below 100° C. in less than or equal to about 30 minutes.Such quenching or flash cooling can maximize the ring closed NMS.

The NMS produced in reactor 34 can be recovered in reactor 38. Reactor38 can be, for example, a distillation unit for separation of NMS frombyproducts including, for example, polymerized material and/or variousequilibrium products shown in FIG. 3. Such distillation can also beutilized to remove fermentation broth components. Polymerized materialand/or equilibrium products of FIG. 3 can be recovered from reactor 38and can be recycled back to reactor 34 for production of an additionalamount of NMS. Methanol and/or water can also be recovered from reactor38 and can optionally undergo separation of water from methanol in, forexample, a distillation reactor 40 where water can be recycled back tosource 30 and methanol can recycle back to alkylating agent source 36.Nitrogen-containing byproducts such as, for example, methyl amine canalso be recovered and separated in distillation reactor 40 for recyclingback to reactor 34.

In addition to the distillation discussed above, purification of NMS inreactor 38 can alternatively comprise one or more of steam distillation,decanting, sublimation, extraction and crystallization. In particularinstances, purification of NMS can be conducted as NMS is formed. Forexample, a single reactor (not shown) can be utilized for conducting thereaction to form NMS and for purification of the NMS. A particularlyuseful combination reactor can be, for example, a distillation reactor.

The purified NMS can be provided to reactor 42 to undergo furtherreaction or can be utilized for production of alternative usefulcompounds. It can be advantageous to purify NMS prior to introducing theNMS into reactor 42 to avoid catalyst poisoning or other negativeeffects of mixture components from reactor 34. Such purification isespecially beneficial where a fermentation broth is utilized sincecomponents of the fermentation broth can decrease or destroy catalyticactivity.

It is noted that under appropriate distillation conditions in reactor38, an amount of NMS recovered from reactor 38 can exceed the initialamount of NMS fed to the reactor. This result is likely due toconversion of one or more of the equilibrium products shown in FIG. 3,which occurs during distillation purification of NMS. An exemplaryconversion of equilibrium product which may occur during distillation isconversion of N-methyl succinamic acid to produce NMS and water.

Hydrogenation of NMS can be performed in reactor 42 in the presence of ahydrogenation catalyst. Hydrogen can be provided into reactor 42 from ahydrogen source 44. The hydrogenation catalyst utilized can be any ofthe hydrogenation catalysts set forth above. Preferably, the catalystwill comprise from about 0.5% to about 5% catalytic metal by weight, andsuch metal will be on a carbon support. In particular instances, thecatalyst will preferably comprise one or more of Ru, Rh and Pt sincethese catalytic metals can enhance conversion from NMS and can enhanceselectivity to NMP. For highly selective and efficient production ofNMP, the catalysts can preferably comprise up to about 5% Rh on a carbonsupport, and can preferably be an edge-coated catalyst.

Additional factors which can affect NMS conversion efficiency andselectivity toward NMP include, but are not limited to, reactiontemperature, hydrogen pressure, initial NMS concentration, catalystloading, stirring rate, reactor residence time, and the reactionsolvent. Due to hydrogen's limited solubility in aqueous media, it canbe preferable that the NMS be converted in an absence of water or in thepresence of very little water. Accordingly, it can be desirable toprovide neat NMS or an NMS in a mixture comprising less than or equal to80% water, preferably less than or equal to 50% water, more preferablyless than or equal to about 20% water, and even more preferable lessthan or equal to about 10% water.

Hydrogenation in reactor 42 can preferably comprise a H₂ pressure offrom about 500 psig to about 2250 psig. It can be advantageous inparticular instances to provide a H₂ pressure of up to about 1500 psigto minimize production of pyrrolidines. Where NMS is hydrogenated in anabsence of solvent, an appropriate reaction temperature can be from atleast 70° C. to less than or equal to about 250° C. Where solvent isutilized, an appropriate reaction temperature can preferably be lessthan or equal to about 250° C.

Conversion of NMS in reactor 42 can result in a product mixturecomprising NMP, 2-pyrrolidinone, pyrrolidine, and methyl pyrrolidine.The reaction can also produce byproducts such as amines and polymerizedmaterial. The resulting mixture from reactor 42 can be introduced intoreactor 46 where over-hydrogenated products such as pyrrolidines,amines, and other hydrocarbons (reaction “lights”) can be removed towaste 48 by flash removal. The remaining mixture from flash tank 46 canbe provided into a reactor 50. Production of high purity NMP can beobtained by, for example, distilling in reactor 50. Alternatively, NMPpurification can comprise one or more of crystallization, ion exchange,extraction and selective adsorption. Such purification can separate NMPfrom remaining methanol and water which can optionally be recycled, andfrom “heavies” such as any polymerized material and/or alternativeequilibrium species shown in FIG. 3. Such “heavies” or equilibriumspecies can be recycled back to reactor 34 for additional NMSproduction. Purification in reactor 50 can additionally separate NMPfrom any 2-pyrrolidinone produced during the hydrogenation reaction.

It can be advantageous to include recycling of polymerized materialsand/or alternative equilibrium species in accordance with the methods ofthe invention to improve the NMP at an overall percent yield of greaterthan 92% by mole, relative to the initial amount of succinate.

EXAMPLES Example 1

N-methyl Succinimide Formation in the Presence of FermentationComponents

Ammonium succinate (at a molar ratio of ammonia relative to succinate of1.2:1) is provided to a reactor in a mixture containing corn steepliquor. The corn steep liquor contains approximately 10% non-watercomponents prior to mixing with ammonium succinate. The mixture isformed to contain approximately 28% ammonium succinate, by weight.Methanol is provided at a methanol to succinate ratio of about 1.5:1.Conversion of ammonium succinate is conducted at 280° C. for 8 hrs.Multiple samples are drawn and results are analyzed to obtain conversionand selectivity information. Analysis after 8 hours indicates asuccinate conversion of greater than or equal to 92.9%. The yield ofN-methyl succinimide (NMS) is greater than or equal to 70%, with acorresponding production of less than 6.4% N-methyl succinamic acid,less than or equal to 1.7% succinamic acid, and less than 0.5%succinimide.

A comparison sample run is conducted utilizing conditions set forthabove with the exception that the corn steep liquor is replaced with anequivalent amount of water (by weight). Analysis after 8 hours indicatesa succinate conversion of 93.7%, with a corresponding 68.3% yield ofNMS, 1.6% N-methyl succinamic acid, 3.4% succinamic acid, and 1.8%succinimide.

These results indicate that conversion of succinate to NMS can beefficiently performed in the presence of fermentation components.

Example 2

Ammonia Adjustment and Thermal Formation of Succinamic Acid fromDiammonium Succinate

Diammonium succinate is provided to a reactor at 50 weight percent inwater. The reactor is filled or pressurized with nitrogen and sealed.The sealed reactor is heated to about 200° C. and thereafter samples arecollected from the reactor every 10 minutes. The samples are analyzed todetermine conversion and selectivity. The results of such analysis areshown in Table 3.

TABLE 3 Diammonium Succinate Conversion and Product SelectivitiesElapsed Diammonium Selectivity to Minutes at Succinate SuccinamicSelectivity to Selectivity to 200° C. Conversion (%) Acid Succinimidesuccinamide Feed 0 0 0 0  0 21.6 84.3 10.5 5.2 10 41.7 78.4 11.8 9.8 2056.8 74.7 11.9 13.4 30 62.7 73.2 11.7 15.1 40 64.8 72.7 11.9 15.4 5065.3 73.9 11.2 14.9

The process can produce an ammonia to succinate ratio of about 1.4:1which is within the preferable range for subsequent formation ofN-methyl succinimide. The described method is useful for production ofsuccinamic acid and/or succinimide which as a reagent can be utilizedfor enhanced NMS production relative to utilization of diammoniumsuccinate.

Example 3

N-methyl Succinimide Formation from Succinamic Acid

Succinamic acid is provided to a reactor at 30% by weight in water.Methanol is provided to the reactor at a 1.5:1 methanol to succinamicacid ratio, and ammonia is added to provide a 0.2:1 ammonia tosuccinamic acid ratio. This represents a 1.2:1 ammonia to succinatespecies ratio due to the ammonia integrated into the succinamic acid.The reactor is filled or pressurized with nitrogen and sealed. Thereactor is heated to 280° C. and maintained at temperature for 10 hoursbefore quench cooling. The product is analyzed to determine conversionand selectivity products. Analysis after 8 hours indicates a succinamicacid conversion of greater than or equal to 96.5%. The yield of N-methylsuccinimide (NMS) is greater than or equal to 77%, with a correspondingproduction of less than 6.1% N-methyl succinamic acid, less than orequal to 5% succinic acid, and less than 1.7% succinimide.

Example 4

Ammonia Adjustment and Thermal Formation of Succinimide from DiammoniumSuccinate

Diammonium succinate is provided to a reactor at 50% by weight in water.The reactor is subjected to vacuum and water is distilled off at 50° C.to yield nearly 100% DAS. The reactor is returned to atmosphericpressure, filled or pressurized with nitrogen, and heated to theindicated temperature and held for the indicated time before cooling thereactor to room temperature. The product is weighed, dissolved in water,and analyzed to determine conversion and selectivity to intermediates.The overall mass balances are observed to be high but not above expectedanalytical tolerances.

TABLE 4 Diammonium Succinate Conversion and Product SelectivitiesElapsed Diammonium Temp. Time at Succinate Selectivity to Selectivity toSelectivity to (° C.) Temp (min) Conversion (%) Succinamic AcidSuccinimide succindiamide 200° C. to 30 93.9 4.6 93.8 n/d 270° C. 200°C. 60 90.8 5.0 96.5 1.5 200° C. 90 93.3 0.1 98.5 n/d 160° C. 480 91.70.1 97.8 n/d 220° C. 30 93.2 2.5 101.5 n/d n/d = not detected

This method forms succinimide with a release approximately half theoriginal ammonia as the DAS cyclizes to form succinimide. The ammonia isremoved in the vapor phase along with water. Accordingly, the processproduces a nearly 1:1 ammonia to succinate ratio. However, the processcan alternatively be stopped at any ratio between 1:1 to 2:1. Thisprocess forms mostly succinimide with some succinamic acid present, eachof which can be favorable intermediates for converting to N-methylsuccinimide.

Example 5

Formation of N-methyl Succinimide from Succinimide

Succinimide is provided to a reactor at 23% by weight in water. Methanolis provided to the reactor at a 1.5:1 methanol to succinimide ratio inan absence of added ammonia. The ammonia integrated within thesuccinimide provides a 1:1 ammonia to succinate species ratio. Thereactor is pressurized with nitrogen and sealed. The reactor is heatedto 300° C. and is maintained at temperature for 5 hours. Samples arecollected at least every hour during the reaction. Product analysis isconducted to determine conversion and product selectivity. Analysis ofthe 4 hour sample indicates a succinimide conversion of greater than orequal to 96%. The yield of N-methyl succinimide (NMS) is greater than orequal to 80%.

Example 6

N-methyl Succinimide Hydrogenation

Approximately 5.0 grams (g) of the specified catalyst is charged into areactor equipped with a magnetic stirrer. Approximately 50.0 g of solidNMS is utilized a feedstock and is provided to the reactor. The reactionis conducted under 1500 psig constant H₂ pressure at a stir rate ofabout 1000 rpm. After 4 hrs, the resulting gas and liquid components areanalyzed for determination of NMS conversion and product selectivity.The results of the determinations are indicated in Table 5 for each ofthe indicated catalysts and reaction temperatures.

TABLE 5 Catalyst Based Hydrogenation Selectivities molar % (oftheoretical) NMP/2- Catalyst No. Temp. % of NMS Yield of pyrrolidinone(from Table 2) (° C.) Converted NMP (Mole Ratio) 1 200 <1 0.6 n/d 2 2007 6.8 25 3 200 3 3 10 4 200 65 55.9 65 6757-09-1 200 84 69.3 10ESCAT-268 200 26 25.7 >90 ESCAT-340 200 45 41.8 149 ESCAT-140 200 1512.4 48 ESCAT-440 200 96 34.3 1.5 ESCAT-440 150 75 42.2 6.5 ESCAT-440120 39 19 n/d ESCAT-340 220 50.2 50.2 70 ESCAT-268 220 35.5 35.5 n/dCo-0138 E 1/16 3F 200 58.6 32.0 18 G 106 B/W 5% Rh 220 95.8 90.8 142*ESCAT-340 200 40.4 38.0 n/d G 106 B/W 5% Rh 220 93.6 89.4 134 2Py =2-pyrrolidinone; n/d = not detected; *reaction was conducted at 2000psig.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understoood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A method of processing an initial compound having a formula (A)

wherein R₁ comprises a saturated or unsaturated, branched or un-branchedgroup containing two or three carbon atoms, and wherein Z and Xindependently comprise one or more of C, H, O, N, S, a halide, and acounter-ion, the method comprising: providing the initial compound;converting at least a portion of the initial compound to a secondcompound having a formula

the converting comprising one or both of thermal and catalyticprocessing; reacting the second compound with an alkylating agent toform a derivative having a formula

wherein R₂ comprises an alkyl group, the derivative being present in amixture comprising one or more additional components selected from thegroup consisting of the initial compound of formula A, the secondcompound, solvent, the alkylating agent, byproducts, and fermentationbroth components; and performing a purification to remove at least someof the one or more additional components.
 2. The method of claim 1wherein X and Z are independently selected from the group consisting ofOR₃, OH, and O⁻ with a counter-ion, wherein R₃ comprises an alkyl group.3. The method of claim 1 wherein the initial compound is selected frommalic acid, maleic acid, fumaric acid, itaconic acid, succinamic acid,succinic acid or a derivative thereof.
 4. The method of claim 1 whereinthe alkylating agent comprises a member of the group consisting of analcohol, a polyol, an acetal, a carboxylate, an alkyl halide, an alkylamine, a carbonate compound, a thiol compound, a thiocarbonate compound,and a sulfate compound.
 5. The method of claim 1 further comprising,prior to the converting, providing the initial compound in an aqueoussolution.
 6. The method of claim 1 wherein the initial compound is adiammonium salt.
 7. The method of claim 1 wherein ammonia is addedduring the converting.
 8. The method of claim 1 wherein ammonia isrecovered during the converting, after the converting or both during andafter the converting.
 9. The method of claim 1 wherein the purificationcomprises at least one of decanting, distillation, sublimation, steamdistillation, extraction and crystallization.
 10. The method of claim 1wherein the additional components comprise a reaction byproduct andwherein an additional amount of the derivative is produced from at leastsome of the reaction byproduct during the purification.
 11. The methodof claim 1 wherein the initial compound is selected from an ammoniumsuccinate and diammonium succinate.
 12. The method of claim 1 furthercomprising, after the purification, hydrogenating the derivative in thepresence of a catalyst to produce at least one member of the groupconsisting of a product having formula (B)

and a product having formula (C)


13. The method of claim 12 wherein the hydrogenating is performed in thepresence of added hydrogen.
 14. The method of claim 12 wherein thehydrogenating produces the compound having the formula (B) and thecompound having the formula (C), the method further comprisingseparation of the compound having formula (B) from the compound havingformula (C).
 15. The method of claim 12 wherein the method additionallyproduces one or both of a compound having formula (D)

and a compound having formula (F)

and further comprising separating the compound of formula (B) from thecompounds having formulas (C), (D) and (E).
 16. The method of claim 1wherein the initial compound is a fermentation product and the providingcomprises providing a fermentation broth.
 17. The method of claim 16wherein prior to the converting, the water content of the fermentationbroth is adjusted to be approximately equivalent to the amount, byweight, of the initial compound present in the mixture.
 18. The methodof claim 16 wherein ammonia is present in the fermentation broth andwherein the ammonia concentration is adjusted to provide a ratio ofammonia relative to the initial compound of less than 2:1.
 19. Themethod of claim 1 further comprising after the purification,hydrogenating the derivative in the presence of a catalyst comprising atleast one member of the group consisting of Fe, Ni, Pd, Sn, Pt, Co, Re,Rh, Ir, Os, Ag, Au, Ru, Zr, and Cu.
 20. The method of claim 19 whereinthe catalyst comprises a support and from about 0.5% to about 5% Rh, byweight.
 21. The method of claim 20 wherein the Rh is edge-coated on thesupport.
 22. The method of claim 19 wherein the derivative is providedto a hydrogenation reactor in molten or solid form and is hydrogenatedin an absence of added solvent.